Tóxico literally means "toxic" in English. While it's a common word, its use in this song is particularly interesting and reflects modern slang.
In the context of the lyrics, the singer uses "tóxico" to describe himself and his behavior, specifically his jealousy and drinking, which are damaging his relationship. It's a self-aware and relatable term for many listeners, making it both engaging and memorable.
Have you ever done something you immediately regretted? In "Qué Pena Contigo," which translates to "What a Shame with You," the singer is dealing with the consequences of his actions. He admits that once again, the drinks "didn't do me well" (los tragos no me hicieron bien), causing him to yell at his partner. He even calls himself "toxic" (tóxico) and realizes this was the final mistake.
This song is a heartfelt apology and a sad goodbye. The singer knows his partner is tired of this behavior and won't forgive him this time. He sings, "Now I've really lost you" (Ahora sí ya te perdí), accepting that his "other half" (otra mitad) is gone for good. He's filled with shame and disappointment, acknowledging that he messed up and lost someone very special.